JP3248934B2 - Unit contact / separation mechanism in electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a unit contacting / separating mechanism in an electrophotographic apparatus for positioning and retracting a developing unit and the like which are detachably provided to the electrophotographic apparatus with respect to a photosensitive member.

[0002]

2. Description of the Related Art Generally, a developing device used in an electrophotographic apparatus is of a type which is unitized and attached to and detached from a main body of the developing device in view of the service life and the frequency of maintenance. As a developing method of obtaining a multi-color or full-color image using such a unitized developing unit, a developing unit of a plurality of different colors is arranged around a photoconductor, and these developing units are mounted on the photoconductor. There is a device which develops the respective colors by holding the developing units in such a manner that they can advance and retreat, and by rotating the cam, each developing unit is sequentially brought into contact with the photosensitive member.

In this case, for example, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Unexamined Patent Publication No. 1 (1993), an elastic body (elastic plate) is provided on the developing unit side, and the elastic body is pressed by a cam so that the developing unit comes into contact with the photosensitive member with a constant force. A contact / separation mechanism is often used.

In the unit contacting / separating mechanism used in such a developing unit, when the developing unit is at the developing position, the gap (developing gap) between the developing roller of the developing unit and the photosensitive member is important. Therefore, a method in which rollers having a diameter slightly larger than the developing roller are provided at both ends of the developing roller, and these rollers are brought into contact with the non-image areas at both ends of the surface of the photoreceptor has a simple structure and is easy to obtain accuracy. It is often used for the following reasons. In this case, in particular, during the developing operation, in order to keep the developing gap between the developing roller and the photosensitive member, it is necessary to press the developing unit with a constant force to contact the roller with the photosensitive member.

From this viewpoint, a specific example of a conventional unit contacting / separating mechanism using rollers at both ends of the developing roller will be described with reference to FIG. In the vicinity of the rotatable photoconductor (partner structure) 1, a developing unit (unit structure) held on a support plate 2 so as to be able to advance and retreat with respect to the photoconductor 1.
3 are provided. In this case, the support plate 2 fixed to both sides of the developing unit 3 on the main body side is formed with two long holes 4, respectively, and these long holes 4 are formed integrally with the developing unit 3. A shaft 3a is supported on the photosensitive member 1 so as to be able to move forward and backward.

Further, the photosensitive member 1 of the developing unit 3
The developing roller 5 is provided on the side, and rollers 6 slightly larger in diameter than the developing roller 5 are provided at both ends of the developing roller 5.

Further, a plate-like elastic member 7 is attached to the rear surface of the developing unit 3 with respect to the photosensitive member 1. A cam shaft 8 is arranged behind the elastic body 7. A plurality of cams 9 are fixed to the camshaft 8, and these cams 9 have a structure in which a disk is eccentric. Further, a spring 10 is interposed between the developing unit 3 and a main unit (not shown).

In such a configuration, the developing unit 3
Is held by the elongated hole 4 of the support plate 2 so as to be able to move forward and backward with respect to the photoconductor 1, and is always pulled away from the photoconductor 1 by the spring 10. And the camshaft 8
, The developing unit 3 is advanced to the developing position or retracted to the non-developing position.

FIG. 5 shows a state in which the developing unit 3 is in the developing position. When the elastic member 7 is pressed by the cam 9, the non-image area on the surface of the photosensitive member 1 6 is contacted with a constant force, and the developing gap G between the developing roller 5 and the photoconductor 1 is accurately maintained. On the other hand, when the cam 9 is rotated by 180 degrees from the developing position shown in FIG.
At the same time, the developing unit 3 is returned to the non-developing position away from the photoconductor 1.

However, in such a conventional unit contacting / separating mechanism, since the elastic body 7 is attached to the developing unit 3 side, the developing unit 3 has a longer life (at the time when the internal developer is used up) and a new developing unit is required. At the time of replacement with the developing unit 3, the elastic body 7 that can still be used is also replaced with the developing unit 3, which is uneconomical.

As a solution to this problem of uneconomics, Japanese Patent Application Laid-Open No. Hei 2-110579 discloses an apparatus in which a mechanism that functions as an elastic body 7 is provided on the side of the apparatus body that does not require replacement. . Further, a unit similar to the unit contacting / separating mechanism of the system described in the publication is proposed by the present applicant. An example of the proposal will be specifically described with reference to FIGS. The same parts as those described in FIG. 5 are denoted by the same reference numerals. FIG. 6 schematically shows the entire configuration of the unit contacting / separating mechanism, in which a rotatable photoconductor 1 is provided. In the vicinity of the photoreceptor 1, there are disposed upper and lower two-stage developing units 3 held on a support plate 2 so as to be able to advance and retreat with respect to the photoreceptor 1. In this case, a plurality of long holes 4 are formed in each of the support plates 2 fixed to both sides of the main body device of the developing unit 3.
A shaft 3a integral with the photosensitive member 1 is supported so as to be able to move forward and backward with respect to the photosensitive member 1.

In the developing unit 3, a developing roller 5 disposed on the photoconductor 1 side is provided.
Rollers 6 slightly larger in diameter than the developing roller 5 are provided at both ends of the developing roller 5, and one end of the developing roller 5 is connected to a drive motor 11.

Further, two upper and lower camshafts 8 are arranged behind the developing units 3 with respect to the photoreceptor 1. These camshafts 8 are rotatably held by the support plate 2, and each of the camshafts 8 is provided with two cams 12. These cams 12 are configured to be rotated by 180 ° by a half-rotation clutch 15 controlled by a magnet 13 provided at one end of the cam shaft 8 and an actuator 14. Further, two springs 10 are provided between the upper and lower developing units 3 and a main unit (not shown).

FIG. 7 shows the structure of a main part of the unit contacting / separating device. A rotation stop pin 16 is press-fitted into the camshaft 8. The cam 12 has an elongated hole 12a.
The camshaft 8 is formed in the elongated hole 12a.
A compression coil spring 17 for urging the cam 12 toward the concave side of the cam 12 is inserted. The cam 12 is sandwiched between the rotation stopping pins 16 and the E-ring 18 from both sides in the thickness direction, whereby the cam 12 is rotated by 180 ° with the rotation of the cam shaft 8 without idling. The structure is

In such a configuration, FIG. 6 shows that the upper developing unit 3 is in the developing position and the lower developing unit 3 is in the developing position.
Indicates a state in which the developing unit 3 is in the non-developing position. In the case of the upper developing unit 3, the cam surface on the convex portion side of the cam 12 is in contact with the rear surface of the developing unit 3 and is inserted into the long hole 12 a of the cam 12. The developing unit 3 is mounted by the attached compression coil spring 17.
Is pressed against the photoreceptor 1 side with a constant force, whereby the rollers 6 at both ends of the developing roller 5 abut against a non-image area on the surface of the photoreceptor 1, and a certain distance between the photoreceptor 1 and the developing roller 5 The development gap is kept accurate. In the case of the lower developing unit 3, the cam surface on the convex side of the cam 12 is directed in the opposite direction to the developing unit 3, and the developing unit 3 is released from the pressing force of the cam 12 and It is held at a remote non-developing position.

That is, FIG. 8A shows a state in which the developing unit 3 is pressed against the photosensitive member 1 at the developing position, and the cam shaft 8 is displaced toward the arrow A from the free state with respect to the cam 12. The developing unit 3 is pressed against the photoconductor 1 by the elastic force of the compression coil spring 17. On the other hand, FIG.
4B shows a state in which the developing unit 3 is separated from the photoconductor 1, and the cam shaft 8 is urged by the compression coil spring 17 to abut one side of the elongated hole 12a.

As described above, in the above proposed example, unlike the conventional method (see FIG. 5), the elastic member 7 is not provided on the developing unit 3 side, and the photosensitive member 1 and the developing roller 5 are provided in the same manner as in the conventional method.
Is maintained constant. Thus, even if the developing unit 3 is replaced due to its life, it is possible to eliminate the uneconomical situation of replacing the elastic body 7 which can still be used. In addition, since there is no space for disposing the elastic body 7 on the developing unit 3 side,
The size of the developing unit 3 can be reduced by the space.

As a modification of the above-mentioned proposal, the present applicant, as shown in FIG. 9, uses a plate-shaped elastic member instead of a compression coil spring 17 (see FIG. 7) between a cam 12 and a cam shaft 8. The developing unit 3 is brought into contact with the photosensitive member 1 with a constant elastic force of the elastic member 19 so that the developing gap between the developing roller 5 and the photosensitive member 1 is accurately maintained. is suggesting.

[0019]

However, in the unit contact / separation mechanism disclosed in Japanese Patent Application Laid-Open No. 2-110579 and the proposed example described above, the configuration around the axis of the cam 12 is complicated, and the processing and assembly thereof are difficult. There is a problem that it takes time. Therefore, the present invention provides a mechanism that functions as the elastic body 7 on the side of the apparatus main body that does not require replacement, and
The purpose of the present invention is to realize, with a simple configuration, the uneconomical problem of exchanging the elastic body 7 with the long life.

[0020]

[0021]

According to the present invention, a plurality of unit structures, which are held on a support plate fixed to the main body device so as to be able to advance and retreat, face the mating structure, and are fixed to a camshaft. By rotating the cam, the convex side of the cam
Is brought into contact with the unit structure, and the unit structure
In the unit contacting / separating mechanism for performing positioning with respect to the mating structure , the convex portion of the cam may be attached to the unit structure.
Due to the repulsive force due to the elastic deformation of the camshaft when contacted.
To push the developing unit toward the mating structure side.
3 is a unit contacting / separating mechanism in the electrophotographic apparatus described above .

[0022]

[0023]

In the present invention, when the unit structure is pressed by a plurality of cams to make contact with the mating structure, the cam shaft is bent with the support plate as a fulcrum, and a constant force is generated by the repulsive force due to its elastic deformation. By contacting the unit structure with the mating structure by force, there is no need to provide an elastic body on the unit structure side as in the conventional method, and an elastic body that can still be used sufficiently when replacing the unit structure due to its life is eliminated. Eliminating the uneconomical effect of replacement can be realized with a simple configuration.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example which has solved the above-mentioned problem will be described with reference to FIG. 6 to 9 are denoted by the same reference numerals, and description thereof is omitted. First, as shown in FIG. 6 described above, the support plate 2 fixed to the main unit has a two-stage unit structure that is held up and down with respect to the photoreceptor 1 as the mating structure. And two upper and lower camshafts 8 rotatably held behind the developing unit 3. FIG. 1 shows the configuration of a main part of the present embodiment. Each of the camshafts 8 has two cams 20 each.
Is provided. In this case, these cams 20 are fixed to the cam shaft 8 via eccentric round holes.
The cam surface on the convex side of the cam 20 is formed of a plate-like elastic body 21 made of metal or resin.

In such a configuration, at the time of development, the cam shaft 8 is driven to rotate by a half-rotation clutch 15 controlled by a magnet 13 provided at one end of the cam shaft 8 and an actuator 14. On the rear surface of the developing unit 3, the elastic body 21 on the convex portion side of the cam 20 is provided.
And the developing unit 3 is pressed against the photoreceptor 1 with a constant force by a repulsive force due to the elastic deformation. This allows
The rollers 6 at both ends of the developing roller 5 are brought into contact with the non-image areas at both ends of the surface of the photoreceptor 1 with a constant contact pressure.
The developing gap between the developing roller 5 and the developing roller 5 is reliably maintained.

As described above, at the time of development, it is possible to press the developing unit 3 toward the photosensitive member 1 with a constant force due to the repulsive force caused by the elastic body 21 on the convex portion side of the cam 20 being elastically deformed. . Thus, the conventional method (see FIG. 5)
It is not necessary to provide the elastic body 7 on the side of the developing unit 3 as described above.

Therefore, eliminating the uneconomical effect of replacing the elastic body 7 that can still be used when the developing unit 3 is replaced due to the service life is described in the aforementioned proposal example (see FIGS. 6 to 9). This can be realized with a simpler configuration. That is, the cam 20 need only be fixed to the camshaft 8 through the eccentric round hole, and the elastic body 21
Only the outer circumference (cam surface on the convex side) of the cam 20 is provided, so that there is no need to perform special processing around the axis of the cam 12 as in the above-mentioned proposed example, thereby facilitating the processing and assembly of the cam 20. Is possible.

[0028] As a modification of this example, as shown in FIG. 2, the rubber-like elastic body cam surface of the convex portion side of the cam 20 2
2 can be implemented similarly.

Next, an embodiment of the present invention will be described with reference to FIGS. 6 to 9 are denoted by the same reference numerals, and description thereof is omitted. FIG. 3 shows a configuration of a main part of the present embodiment. A support plate 2 fixed to a main body device is rotatable rearward of a two-stage upper and lower developing unit 3 which can move forward and backward with respect to the photoreceptor 1. And two upper and lower camshafts 23 are provided. These camshafts 23 are formed thin to have flexibility, and each of the camshafts 23 is provided with two cams 24, respectively. In this case, these cams 24 are fixed to the cam shaft 23 via eccentric round holes. As shown in FIG. 4, the cam surface of the cam 24 is formed in an arc shape having a large diameter at the center in the thickness direction and small diameters at both ends.

In this configuration, FIG. 3A shows a state in which the cam 24 is in contact with the rear surface of the developing unit 3, and the developing unit 3 and the cam surface on the convex side of the cam 24 come into contact with each other. The camshaft 23 is bent with the support plates 2 on both sides as fulcrums, and the developing unit 3 is pressed against the photoreceptor 1 with a constant force by the repulsive force due to the elastic deformation of the camshaft 23. As a result, a fixed developing cap between the photoconductor 1 and the developing roller 5 is accurately maintained. In this case, by forming the cam surface of the cam 24 in an arc shape in the thickness direction, the cam shaft 23 is formed.
The cam 24 is prevented from contacting one side due to the deflection of the cam unit 24 so that the cam 24 surely comes into contact with the rear surface of the developing unit 3.

On the other hand, FIG. 3B shows a state in which the cam 24 has been rotated by 180 ° from the state shown in FIG. 3A, and the cam surface on the convex side of the cam 24 is in the opposite direction to the developing unit 3. The camshaft 23 is kept straight without being bent. At this time, the developing unit 3 is released from the pressing force of the cam 24 and returned to the non-developing position away from the photoconductor 1.

As described above, the developing unit 3 can be constantly pressed against the photosensitive member 1 with a constant force by the repulsive force due to the elastic deformation of the cam shaft 23. This eliminates the need to provide the elastic body 7 on the developing unit 3 side as in the conventional method (see FIG. 5).

Therefore, it is possible to eliminate the uneconomical problem of replacing the elastic member 7 when the developing unit 3 is replaced due to the service life, as described in the above-mentioned proposal example (see FIGS. 6 to 9).
This can be realized with a simple configuration as compared with. That is, in order to make the cam shaft 23 flexible,
It is only necessary that the cam 24 be fixed to the camshaft 21 through the eccentric round hole, so that there is no need for special processing around the axis of the cam 12 as in the proposed example.
Compared to one embodiment of the described invention (see FIGS. 1 and 2),
Processing and assembly of the cam 24 can be further facilitated.

The unit contacting / separating mechanism described above is
Although the description has focused on the operation of moving the developing unit 3 to and from the photoconductor 1 during multi-color development, the present invention is also applied to other unit structures that move toward and away from the photoconductor 1 such as a cleaning unit and a transfer unit. Is possible.

[0035]

[0036]

According to the present invention, a unit structure held movably on a support plate fixed to the main body side is a mating structure.
To face the provided times a plurality of cams secured to the cam shaft
By rotating, the convex side of the cam is
The counterpart structure of the unit structure being brought into contact with the structure
In the unit contacting / separating mechanism that performs positioning with respect to the above, when the convex portion of the cam comes into contact with the unit structure,
The developing unit is repelled by the elastic deformation of the camshaft.
An electrophotographic apparatus which presses the
Since the unit moving mechanism in location, the time of contact with the mating structure by pressing the unit structure by a plurality of cams, flexes the camshaft support plate as a fulcrum, by the repulsive force due to the elastic deformation It is possible to always bring the unit structure into contact with the mating structure with a constant force,
This eliminates the need to provide an elastic body on the unit structure side as in the conventional method, and simplifies eliminating the uneconomical situation of replacing a sufficiently usable elastic body when the unit structure is replaced due to its life. It can be realized by the configuration.

[Brief description of the drawings]

FIG. 1 is a side view of a cam showing an example in which a conventional problem is solved .

FIG. 2 is a side view showing a modification of the cam of FIG.

3A and 3B show one embodiment of the present invention, and FIG. 3A is a partial plan view showing a state where a cam is in contact with a unit structure;
(B) is a partial plan view showing a state where the cam is separated from the unit structure.

FIG. 4 is a vertical sectional front view showing a shape of a cam surface of the cam shown in FIG. 3;

FIG. 5 is a side view showing a conventional example.

FIG. 6 is a perspective view showing an example proposed by the present applicant.

7 shows a configuration of a main part of the cam of FIG. 6,
(A) is a side view of the cam, and (b) is a front view thereof.

8 (a) is a partial front view showing a state in which the unit structure comes into contact with a mating structure, and FIG. 8 (b) is a partial front view showing a state in which the unit structure comes into contact with the mating structure. FIG. 4 is a partial front view showing a state away from the front.

FIGS. 9A and 9B show a modification of FIG. 7, wherein FIG. 9A is a side view of the cam, and FIG. 9B is a front view thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Companion structure 2 Support plate 3 Unit structure 8,23 Cam shaft 20,24 Cam 21,22 Elastic body

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-288859 (JP, A) JP-A-2-148076 (JP, A) JP-A-62-15757 (JP, A) Jpn. 10745 (JP, U) Japanese Utility Model Showa 51-92724 (JP, U) Japanese Utility Model Showa 64-6668 (JP, U) Japanese Utility Model Utility Model 3-96664 (JP, U) (58) Field surveyed (Int. ^7, DB name) G03G 15/00 G03G 15/01 G03G 15/08 G03G 21/16 - 21/18 F16H 53/00 - 53/08

Claims (1)

(57) [Claims] 1. A unit structure held movably on a support plate fixed to a main body device side to face a mating structure.
Te provided, this rotating a plurality of cams secured to the cam shaft
Abuts the convex side of the cam to the unit structure
By the unit moving mechanism for performing position <br/>-decided Me against the mating structure of the unit structure, the convex of the cam
Of the camshaft when the unit comes into contact with the unit structure
The developing unit by the repulsive force due to the
An electronic device characterized by being pressed toward the hand structure side
Unit contact / separation mechanism in photographic equipment .